Concrete tamping apparatus



Feb. 6, T J OWEN CONCRETE TAMPING APPARATUS Filed May 20, 1931 3 Sheets-Sheet l Feb. 6, 1934. J OWEN 1,945,563

CONCRETE TAMP ING APPARATUS Filed May 20, 1931 I5 Sheets-Sheet 2 4/ 42 4/ Feb. 6, 1934. OWEN 1,945,563

CONCRETE TAMP ING APPARATUS Filed May 20, 1931 3 Sh ts-Sheet 3 Patented Feb. 6, 1934 UNITED STATES PATENT OFFICE .6 Claims.

This invention relates to the art of making slabs of plastic material and especially concrete.

My invention has for its object to provide an improved apparatus for manufacturing such articles, including reinforced concrete slabs of the type disclosed in my prior Patent 1,797,295 or anything of a generally similar character.

In the succeeding description and the accom panying drawings I have set forth a preferred embodiment and mode of practicing the invention, but it will be understood that rather wide variations may be made in the particular operations performed by the machine and in the form and mechanical arrangement of parts, and that features could be added or omitted without departing from the scope of the invention as defined in the claims.

The apparatus as herein illustrated, briefly stated, comprises a series of tampers operating on the trip-hammer principle and arranged in two rows, together with means for elevating and releasing the tampers in rapid succession to effect a reduction in the thickness of the plastic material, the action proceeding progressively from one end of the slab to the other, the tamping action in one row of tampers preferably preceding that in the other row and the effect being to increase the density of the concrete mixture and to expel the air from within said mixture and from between it and the slab mold.

I prefer to operate with a comparatively dry mixture, by which is meant one having such water content that substantially all of the water is retained in the mixture during the tamping operation and little or none of it will be driven to the surface as a result of such operation.

My invention includes an improved means for concurrently lifting the tampers in both rows out of the range of their operating cams. While they are thus lifted, after the concrete has been tamped in the mold, a smoothing plate is introduced by gravity on suitable guides between the tampers and the mold and the mold is then reciprocated longitudinally beneath said smoothing plate to level the top surface of the slab, the reciprocating device consisting of an endless chain engaging the mold and adapted to be operated by hand during the smoothing operation and also by power for the purpose of moving the mold from the loading to the tamping position and from the latter to the discharging position.

For supporting and guiding the mold in its several positions at the front of the machine, I provide a roller conveyor or platform, and at the discharge position there is located an ejector device for elevating the bottom plate of the mold with the formed slab thereon out of the frame member of the mold so that the slab on said bottom plate may be removed for setting and drying the concrete.

At the back of the machine is located a second roller conveyor or platform for returning the mold frame from the discharging to the loading position, and at the former position is also provided a device for elevating said mold frame clear of the rollers in the front conveyor and supporting and guiding it while it is being slid over the rear conveyor and then depressed upon the rollers of the latter. A similar elevating and guiding device is located at the loading position for use in shifting the mold frame onto the front conveyor.

0f the accompanying drawings Fig. 1 is a front elevation of a slab-making apparatus embodying and adapted to carry out my invention, omitting the parts at the loading end, to the right of the line AA.

Fig. 2 is a front elevation of the parts to the right of said line.

Fig.3 is a left-hand end elevation.

Fig. 4 is a right-hand end elevation.

Fig. 5 is a transverse section on the line 5--5 of Fig. 1.

Fig. 6 is a section on the line 66 of Fig. 5.

Fig. '7 is a top plan view of the parts shown in Fig. 1'.

Fig. 8 is a top plan view of the parts shown in Fig. 2.

Fig. 9 is a partial vertical section looking toward the front of the machine from the line 9-9 of Fig.- 1, showing the mold and its chain propelling device and associated parts.

In the drawings, 10 indicates a two-part slab mold consisting of a rectangular frame 11 whose vertical walls act as molding surfaces for the edges of the slab, and a removable bottom molding plate 12 formed with longitudinal grooves or channels 13 for molding ribs on the lower side of the slab, said plate being supported on the horizontal bottom wall 14 of the mold frame member. The under side of said mold frame is provided with flat-bottomed ribs 11 for running on the conveyor rollers.

Fig. 5 shows the formed slab 15 of raw concrete mixture in the mold, and the metallic reinforcing rods 16 embedded in the slab coincidently with the ribs thereof.

On a frame 17 having a relatively high middle portion 18 and relatively low end portions 19, 20 are mounted the several parts of the apparatus.

Extending horizontally along the front of the machine is a mold-supporting and guiding platform of the roller conveyor type comprising anterior, middle and posterior portions having rollers 21, 22, 23 freely journaled between members of the frame portions 19, 18, 20 respectively. At the back of the machine is a similar roller conveyor or platform parallel with the front conveyor and including rollers 24 for returning the empty mold frames 11 from the discharging. to the loading position, either by hand pressure, or by gravity if said rear conveyor is inclined downwardly toward the loading position.

Above the tamping position of the mold on the rollers 22 of the central frame member 18 are mounted two parallel rows of vertically-movable tampers 25 of the trip-hammer type each consisting of a lower tamping head 26 attached to a flat vertical stem or lifting bar 27 provided with a pair of oppositely-mounted rollers 28 adapted to be engaged by one of a series of forked cams 29 mounted in two rows upon a pair of parallel cam shafts 30, 31. Said cam shafts at their lefthand ends as viewed from the front of the machine carry respective worm gears 32, 33 meshing with worms 34, 35 upon a transverse shaft 36 having a pulley connected by a belt 3'7 with a smaller pulley on the shaft of an electric motor 38 for furnishing power to drive the tampers and other parts. The lifting bars 27 of the tampers are guided by upper and lower sets of guide plates 39, 40 suitably notched or recessed at intervals to receive the edges of said lifting bars. To obtain the maximum length of stroke for the tampers, the rollers 28, in the lowest positions of said tampers, are located substantially no higher than the cam shafts 30, 31, thus obtaining the maximum kinetic force of the reciprocating masses without requiring the use of springs or unduly heavy tampers. As clearly seen in Fig. 1, each of the tamping heads is laterally separated from the adjacent one of the series by a substantial space-about one-half inch in practice-so that the tamping areas on the surface of the concrete are correspondingly spaced, to permit the upward escape of a portion of the air in the concrete from between the tamping heads when the latter are in their lowest positions.

The cams 29 on each of the cam shafts are placed at different angles in a regular succession through substantially a complete circle so that their tips lie along a steep-pitched helical line. The result of this arrangement is that the individual tampers are raised by their cams and then dropped to impose a compacting blow upon the wet concrete in the mold underneath them and the action proceeds progressively from one end of the mold to the other in a vertical faced or half wave, the back of which is formed by about four of the tampers lifted to varying heights at the same time. In the arrangement shown, the wave in the back row of tampers proceeds in advance of that in the front row by about onethird of the length of the mold so that the tamping blows are exerted at different points on each half of the width of the concrete body. However, I do not wholly confine myself to this staggered timing. I do, however, find it an advantage to employ two rows of tampers for a slab of approximately 18 inches in width, because a single tamper extending across the full width of such a slab displaces so much air from between its face and the concrete in striking the latter as to cause objectionable spattering of the material at its upper surface.

For concurrently elevating all of the tampers at the same time, out of the range of their cams, the upper end of each tamper bar 27 is provided with a pin 41 projecting leftwardly, as viewed in Figs. 1 and 7, over the edge of a transverse angle bar or slat 42 attached to a longitudinal supporting plate 43 which is suitably guided for vertical movement, there being one of these slats for each pair of lifter bars. On the under side of the plate 43 is a collection of spaced rollers 44 having heads at their ends as seen in Fig. 5 to hold them against axial movement, and under these rollers is a pair of horizontal angle irons forming an elevating bar 45 pivoted to the upper ends of a series of swinging arms or links 46 whose lower ends turn upon fixed pivots on the machine frame, the bar being moved longitudinally to swing the links and raise or lower said bar by means of a hand lever 47 linked thereto by its short arm and pivoted on the machine frame. In the final operative positions of the links 46, they stand upright, substantially parallel with the line of motion of the tamper bars 27, as indicated in full lines in Fig. 1, so as to sustain said bars in their elevated positions without the use of a catch.

When the bar 45 is moved upward and to the right as viewed in Fig. 1 and there held by a suitable stop, the links 46 are slightly past their vertical positions to avoid accidental dropping of the elevating bar, and the entire collection of tampers is raised to the full-line positions to carry their rollers 28 out of range of the cams 29. For depressing the tampers to their operative positions the elevating bar is moved downwardly and to the left by means of the hand lever 47 to bring it and the links 46 to their broken-line positions as seen in Fig. 1.

48 is a flat rectangular troweling smoother plate having about the same area as the top of the mold and adapted to be introduced over said mold from the back of the machine when the tampers 25 are elevated. Said plate is attached by means of angle bars 49 to transverse back bars 50, the two end ones of which are each connected by a pair of suspending barsv 51 of different lengths with roller trolleys 52 mounted to run in tracks or guide rails 53 whose rear ends are pivoted at 54 to fixed frame members. These guide rails are moved by a rocker-shaft 55 having short arms 56 linked to the front ends of the rails and a long handle-arm 57 for turning said shaft. When in their'full-line position shown in Fig. 5 and in Figs. 3 and 4, the guide rails are inclined above a horizontal plane so that the smoothing plate 48 tends to roll by gravity to its inoperative position at the rear of the machine. When the guide rails are depressed to a position inclined below the horizontal plane as indicated by broken lines in Fig. 3, the smoothing plate 48 will roll forwardly to a position over the mold, after the tampers have been elevated. When in this position, owing to the use of front suspending rods 51 which are shorter than the rear ones, the plate 48 from front to rear will be in a substantially horizontal position as seen in broken lines in Fig. 3.

For propelling the mold from the right as viewed in Fig. 1, into and through its tamping position, and for longitudinally reciprocating it under the smoothing plate 48 when in that position, to produce a troweling action of said plate upon the upper surface of the concrete in the mold, I provide an endless chain carrier 58 whose upper stretch extends longitudinally over the platform rollers 22 and whose links are adapted to engage lugs 59 projecting downwardly from the bottom of the mold frame 11 at both ends of the latter. This chain turns around two of the conveyor rollers of which the one 22 is flanged to guide the chain in a path centrally of the rollers. The lower stretch is guided by an additional small roller 60, and a driving sprocket 61 for the chain is provided on a transverse power shaft 62 connected through suitable gearing 63, 64, shafts 65, 66 and worm 6'7 with a worm gear 68 loosely mounted at one end of the rear cam shaft 31, said worm gear being adapted to be coupled with the shaft by a friction clutch 69 having a con trolling hand lever 70. The sprocket shaft 62 also has a hand wheel 71 fixed to its front end for manually operating the chain 58 back and forth to effect the slab-smoothing operation when the clutch 69 is disconnected.

At the discharging position of the mold 10, where it. rests on the rollers 23 at the left of the machine, I provide a pair of ejector bars '72 movable upwardly through openings 73 in the bottom wall of the mold frame 11 and each mounted on a pair of lifter rods '74 which are suitably guided for vertical movement on the frame section 20. Each of said rods carries a pair of rollers '25 adapted to be engaged by a forked arm 76 upon a rock-shaft '77, the two rock-shafts having arms 78 connected by a link 79 and the shaft at the left also having a handle-arm 80 for turning these shafts to raise and lower the ejector bars 72. The upward movement of said bars through the mold frame openings 73 causes the mold plate 12 carrying the formed slab 15 to be lifted out of the frame 11 as shown in broken lines in Fig. l, whereupon the plate and slab can be manually carried off for drying and setting of the slab. The ejector bars are then depressed and the empty mold frame can be pushed onto the rear conveyor and returned over the rollers 24 thereof to the loading position.

To facilitate the shifting of the mold frame from the front to the rear conveyor at the discharge position, by lifting it free of the rollers, I provide a pair of guide rods 81 extending over both conveyors between adjacent rollers thereof and eccentrically pivoted between the longitudinal frame bars. These guide bars are provided with arms 82 having loose pivotal connections with the outer ends of a pair of horizontal links 83 whose adjacent ends are loosely connected with a pin 84 on the short arm of a hand lever 85 pivoted to the frame at 86. When the longer front arm of said hand lever is grasped and swung to the left as shown in Fig. '7, the eccentrically-mounted guide rods 81 are turned to depress their upper sides and allow the mold frame 11 to rest on the rollers 23 or 24. When said hand lever is moved in the opposite direction the guide rods raise the mold frame clear of said rollers and allow it to be pushed over on the rods to the rear conveyor. A similar mechanism for raising and lowering the mold frame is provided at the loading position as indicated in Fig. 8, said mechanism including eccentric guide rods 81 hand lever 85*- and connecting arms and linkage.

In the operation of my invention, an operator is stationed at the loading position at the right for receiving the empty mold frames 11 at the end of the rear conveyor, operating the eccentric guide rods 81 by means of the hand lever 85 to lift the mold frame free of the conveyor rollers, drawing it forward over the front conveyor, lowering it onto the rollers thereof, then placing bottom mold plates 12 therein and charging each mold with wet concrete from a mixer,

the mold is on the front conveyor.

to a level somewhat above its upper edge, while Another operator is stationed at the front of the machine to control the operation of the tampers, the propelling chain, the slab-smoothing means and the ejector.

This second operator, while the tampers 25 are raised to their inoperative positions by means of the elevating bar 45, manually advances the charged mold until its forward lug 59 engages between the links'of the chain 58. He then connects said chain with the power furnished by 'the'constantly-running motor 38 through the intermediate connections including the cam shaft 31, by engaging the friction clutch 69, whereby said mold is moved forward to its tamping position over the middle set of conveyor rollers 22, and the clutch is then disengaged to stop the chain;

By manipulating the handlever 47, the tampers are then lowered to bring their rollers 28 within the range of the cams 29 which lift and drop said tampers successively in the manner previously indicated. The wet concrete, which, as already stated, is of a relatively dry consistency so that substantially all of its water will be retained under the action of the tampers, is thereby compacted to close up its voids and expel the air fromwithin the concrete and from between it and the mold surface, a part of the air escaping upwardly from the concrete body through the spaces separating the adjacent tamper heads. The progressive or wave-like action of the tampers in this connection increases the efficiency of the compacting and air-expelling action as compared with other modes of tamping, and greatly reduces the amount of pitting of the lower surface of the slab by trapped air bubbles which would mar the appearance of the product, the expulsion of air from within the slab also serving to increase its strength.

In this machine the tamping of the slab may occupy about one minute. When it is completed, the tampers are again elevated to their inoperative positions, whereupon the operator swings the handle 57 upwardly to depress the guide rails 53 and allow the smoothing plate 48 to roll forwardly by gravity to a position over the mold between the latter and the tampers and to rest on the upper surface of the slab. Then by oscillating the hand wheel 71 and moving the chain 58 back and forth the mold and its contents are reciprocated under the smoothing plate to smooth out the ridges left by the spaced tampers and level off the top surfaceof the concrete by the troweling action of said plate 48, which also causes a settling and further densification of the material by reason of the repeated back and forth motion.

When the smoothing is completed, the operator again connects the chain 58 with the power through the clutch 69 and the filled mold is advanced from under the tampers to its discharging position upon the rollers 23 as shown in Fig. l, the last part of its movement to this position being performed by hand after the posterior lug 59 on the mold frame has become disengaged from the chain. The handle-arm 80 is then swung to the right to elevate the ejector bars 72 and raise the mold plate 12 and slab 15 out of the mold frame 11, the plate with the slab on it is removed and the ejector bars are depressed to their original positions. The mold frame is then lifted off of the rollers 22 by moving the handle end of lever 85 to the right to turn the lid eccentric guide bars 81 upwardly, the mold frame is pushed back on the guide bars over the rear conveyor, is allowed to descend upon the rollers 24 thereof by reversing the lever 85, is then returned over said rear conveyor to the loading position and the cycle is repeated. In practice, two or three of the mold frames 11 may be kept circulating in the apparatus and a sufficient number of the molding plates 12 is provided to take care of the output of the machine through the slab-forming and the setting and drying stages.

I claim: 1

1. Slab-making apparatus comprising a concrete slab mold, a series of tampers spaced from each other for tamping the concrete over adjacent areas spaced by ridges, means positioned between the tampers and mold for smoothing out the ridges, and mechanism for relatively reciprocating said mold and means in a horizontal direction.

2. Slab-making apparatus comprising a slab mold, means for supporting said mold while being tamped, a troweling plate having a smooth lower surface and inoperatively positioned at one side of the mold, and guiding means for introducing said plate laterally over the mold and lowering it upon the contents thereof and returning it to an inoperative position.

3. Slab-making apparatus comprising a slab mold, means for supporting said mold while being tamped, a series of tampers mounted over said supporting means, a slab-smoothing plate, a pair of pivoted guides movable to oppositely-inclined positions for introducing said plate by gravity between the tampers and the mold and returning mold,v means for supporting said mold in position to be tamped, a troweling plate adapted to be located over the mold in its tamping position, an endless chain having positive propelling means for engaging the mold and moving it into and through said position and for horizontally reciprocating the mold under said troweling plate to level the top surface of the slab, and

- means for reciprocating said chain.

6. Slab-making apparatuscomprising a series of tampers, means for guiding and supporting a slab mold in; an operative position beneath said tampers and in loading and discharging positions respectively anterior and posterior thereto, said means including a roller conveyor structure at the-discharging position, a second roller conveyor structure for returning a discharged member of the mold to loading position, and. means at the discharging position for elevating the discharged mold member above the rollers of the first conveyor structure, for guiding it over those of the second conveyor structure and for lowering it upon the latter.

.. L, THOMAS J. OWEN. 

